When I'm learning to use qsort to sort an array of string, there is a question puzzled me. For example, to sort the following s char *s[] = { "Amit", "Garima", "Gaurav", "Vaibhav" }; To use the qsort, you must provide a comparison function like the following function cstring_cmp I guess in the qsort function, the type of parameter to be passed to the function cstring_cmp is char**. How to convert a char** to a void*? Why can we convert a char** to a void*? int cstring_cmp(const void *a, const void *b) { const char **ia = (const char **)a; const char **ib = (const char **)b; return -strcasecmp(*ia, *ib); /* return the negative of the normal comparison */ }